1. Field of the Invention
The present invention relates to a method for producing a single crystal diamond film. In particular, the present invention relates to a method for producing a single crystal diamond film having good crystallinity, a smooth surface, and good electrical and optical characteristics.
2. Description of the Related Art
Diamond has a large forbidden band width, a large electron mobility, a large hole mobility, a large saturation electron mobility, a large thermal conductivity, a low dielectric constant and high clarity. Therefore, the diamond is highly expected as a material for semiconductors, for example, semiconductive elements having heat resistance and radiation resistance and high speed high output semiconductive elements, and as an element for emitting blue light or UV light.
Recently, R. Mania et al proposed a method for synthesizing diamond in a vapor phase which comprises decomposing and exciting a raw material comprising a hydrocarbon gas such as methane with radiofrequency discharge (R. Mania et al, Crystal Research and Technology, 16, 785 (1981)).
For example, when methane and hydrogen gas are supplied as raw materials under such condition that the methane concentration is 1% or less, a good quality single diamond film containing no graphite component can be grown on a silicon substrate. However, in case where the single diamond film is epitaxially grown on a single crystal diamond substrate, when the thickness of the single diamond film exceeds 1 .mu.m, the film is cracked or abnormally grows (Kagakugijutsu-cho, Muki-zairyo Kenkyusho Kenkyuu Houkokusho, Vol. 39, 39 (1984)).